These 18 Tiny Dots Are A Huge Deal To NASA’s Webb Space Telescope

With the image array in hand, engineers were able to make tiny tweaks to each of the 18 mirror segments so they were lined up relative to each other exactly correctly. They made adjustments to all of the primary mirror segments, as well as the secondary mirror which is a smaller round mirror located on the end of a boom. When this process, called segment alignment, was complete, the engineers could stack each dot on top of each other so that light from each segment was pointed to the same location. This was done by tweaking mirrors in groups of up to six and adjusting them until all the points of light were overlapping.

That means that all of the starlight from the target star, HD 84406, is now hitting one place on the camera detector, and the primary mirror is now working as one big mirror instead of 18 smaller mirrors. It’s not the end of the process, however, as the team still have to line up the segments with extreme accuracy to ensure the telescope can detect even very faint light from distant targets.

“We still have work to do, but we are increasingly pleased with the results we’re seeing,” said Lee Feinberg, optical telescope element manager for Webb at NASA’s Goddard Space Flight Center (via NASA). “Years of planning and testing are paying dividends, and the team could not be more excited to see what the next few weeks and months bring.”